The present invention relates generally to the field of instruments for insertion into a body cavity. More specifically, the present invention relates to instruments which are used to remove foreign bodies from the urethra and bladder.
The prostate is a walnut-sized gland that extends around the urethral lumen from the neck of the bladder to the pelvic floor. Because of the close relationship of the prostate to the urethra, enlargement of the prostate, usually referred to as hyperplasia or hypertrophy, may fairly quickly obstruct the urethra, particularly if the hyperplasia occurs close to the lumen. Such an obstruction inhibits normal micturition, which causes an accumulation of urine in the bladder.
Various methods of treatment for hyperplasia of the prostate gland have been developed. Recently, methods of treatment have been developed comprising the steps of transurethrally inserting and positioning a tubular stent within a restricted portion of the urethra. The use of such implantable stents for dilating the urethra is disclosed in detail in U.S. Pat. No. 4,762,128 issued to Robert F. Rosenbluth on Aug. 9, 1988, the disclosure of which is hereby incorporated by reference in the present case. This method has significant advantages over previous surgical methods of treatment of hyperplasia including a significant reduction of many complications including impotence, incontinence, bleeding, infection, residual urethral obstruction, urethral stricture, and retrograde ejaculation. Accordingly, use of this method is becoming increasingly widespread.
The tubular stents associated with the aforementioned method are generally designed to remain in place indefinitely. However, removal of the stent may occasionally be required. For example, the stent may have been placed poorly, or it may have drifted out of its appropriate location. Removal of the stent may also be required if complications, such as infection, bleeding or urethral stricture, develop.
Open surgical removal of the stent whereby an incision is made to expose the stent for removal under direct vision is one option when removal of the stent is desired. However, use of such surgical methods are highly invasive and may involve significant patient discomfort, a potentially long hospital stay, and a not insignificant rate of morbidity. Therefore, such surgical procedures are, preferably, avoided.
Thus, notwithstanding the availability of surgical procedures for the removal of foreign objects from the prostatic and urethral environment, a less invasive procedure which would reduce or eliminate the occurrence of complications from surgery would be of significant value. In this regard, a procedure for entering the prostatic environment through the natural opening of the urethra would avoid the need for making an incision into the patient. It is important that such a procedure minimize trauma to the soft tissues of the urethral lining. Additionally, a means for easily locating both the object to be removed and the removal instrument would preferably be provided to minimize the time and difficulty of the procedure. Moreover, it would be desireable to have a plurality of techniques available which can be successively attempted without delay, in the event one technique was unsuccessful. The availability of a plurality of techniques would allow surgery to be used only as a last resort.
One prior art method used for the removal of foreign bodies and pieces of tissue from the urethra, bladder or other body cavity comprises transurethrally inserting a forceps through a cystoscope-urethroscope sheath, grasping the foreign body with the forceps under the vision of a transurethral telescope, and pulling the foreign body through the sheath. Such forceps, sheaths and telescopes are available, for example, from Karl Storz Endoscopy-America, Inc., Culver City, Calif. The foreign body may require substantial crushing and/or breaking in order to fit through the sheath when this prior art method is practiced. Many of the stents useful in the treatment of hyperplasia are too large and/or rigid to be effectively pulled into the sheath with the available forceps. Moreover, even where removal of the stent with these devices is possible, it is only possible with much patience and effort. It is desirable to perform these procedures as rapidly as possible, in order to avoid complications and patient discomfort. Additionally, in the event use of the forceps is not successful in removing the stent, an emergency open surgery may be necessary.
Another prior art procedure that has been used in removing kidney stones and other foreign bodies from the bladder makes use of what have come to be called stone baskets. These stone baskets are comprised of two or more flexible wires forming a "basket" into which the stone or other foreign body may be trapped. The baskets are then pulled into a transurethral sheath which is then removed. However, stone baskets are not capable of crushing kidney stones or other foreign bodies trapped by the basket. Removal of larger objects requires the use of a forceps or other tool prior to use of the stone basket to break up and/or crush any objects which will not fit through the sheath. Breaking the object into pieces, also, necessitates the removal of many pieces, taking additional time. Moreover, it may be difficult to ascertain that all of the pieces have been removed. Thus, there is a need for a more rapid and effective means for removal of foreign bodies from the urethra and/or bladder.
Cutting loops have been used in the surgical treatment of hyperplasia of the prostate and other urological conditions. These sharp, rigid prior art loops have been adapted to fit through a transurethral sheath in a nonsecured fashion. The cutting loops have been used for cutting undesired tissue, however, such loops have never been adapted for the removal of foreign objects.